Monitoring communication network performance is a requirement for well-performing communication networks. On some operators' networks, the operator deploys a third party signaling monitor which can capture all the incoming/outgoing site traffic and provide statistic results related to key performance indicators (KPIs), which is schematically shown in FIG. 4. In particular, FIG. 4 shows a site switch 401 which is on the one hand coupled to a third party signaling monitor 402 and on the other hand to a plurality of mobile switching centers (MSCs) 403, 404, and 405. The signaling monitoring system is a powerful tool to open service test in telecommunication network, complaint handling of subscribers, network failure position, and network and service analysis. It collects all kinds of signaling data through different ways without influence on network, such as high impedance cross connection, port mirror, TAP and optical splitter and so on.
Except the bulk tracing capability, the signaling monitor can also trace the messages for a specified subscriber. For example, if the temporary mobile subscriber identity (TMSI) of the specified subscriber is known in advance, the base station system application part (BSSAP) signaling or radio access network application protocol (RANAP) signaling for this subscriber can be filtered out.
To trace all messages for a specific subscriber the signaling monitor needs to decode all messages to a certain extent. It also has to mimic the call processing of the MSCs to correlate messages on the different protocol interfaces to call procedures and to correlate call procedures to the trace session of the specific subscriber. This is problematic as the signal monitor does not have the temporary call identifiers of a subscriber, so it may be difficult or even impossible for the monitor to correlate the signaling on different interfaces of a call procedure. The resulting complexity and the capacity requirements for such a signaling monitor can therefore become substantial if not prohibitive.
Known monitoring function (subscriber tracer) integrated with a network node has the following disadvantages:
(1) The integrated subscriber tracing function has load impact on the network node itself when a lot of subscribers are monitored at the same time.
(2) The trace or monitoring output provided by the network node only contains the application layer payload without the information of transport layers, such as signal connection control part (SCCP), message transfer part 3 (MTP3), or IP layers (see e.g. 3GPP TS 32.423).
(3) The monitoring occurs on node rather than network level, i.e. such level of monitoring does not provide for a global view, e.g. when the subscriber moves across multiple network nodes.